Service providers often forward data traffic to and from their customers in network environments. For example, an Internet Service Provider (ISP) may have a network that includes multiple Provider Edge (PE) routers. In this example, the PE routers may include physical links that facilitate communication for various Ethernet Virtual Private Networks (EVPNs) that correspond to the ISPs' customers. When a PE router associates a new EVPN with a physical link, this PE router may need to notify the other PE routers of the association in order to direct the EVPN's data traffic toward the physical link. Similarly, when a PE router disassociates an EVPN from a physical link, this PE router may need to notify the other PE routers of the disassociation in order to divert the EVPN's data traffic from the physical link.
These PE routers may notify one another of certain route changes by advertising such changes via update messages. For example, a PE router may generate a Border Gateway Protocol (BGP) message that identifies various EVPNs whose data traffic is currently routed through a physical link. The PE router may then disseminate this BGP message to the other PE routers via the ISP's network. These other PE routers may update their forwarding tables to direct the EVPNs' data traffic toward the associated physical link in response to the BGP message.
These update messages, however, may have certain limitations. For example, BGP messages may be limited to 4096 bytes (4K) of data. As a result, in the event that the amount of data needed to advertise the EVPNs exceeds the 4K data limit of a single BGP message, the PE router may attach those EVPNs' information (sometimes referred to as “route targets”) to multiple BGP messages. In this example, one of these BGP messages may include the full 4K of data, and another one of these BGP messages may include the remaining data. The PE router may then disseminate these BGP messages to the other PE routers via the ISP's network. These other PE routers may update their forwarding tables to direct the EVPNs' data traffic toward the associated physical link in response to the BGP messages.
Once the PE router disassociates an EVPN from the physical link, the PE router may remove a route target representing that EVPN from the corresponding BGP message. For example, the PE router may remove a route target representing an EVPN from the BGP message that includes the full 4K of data, thereby potentially making room for another route target in the BGP message. In the event that only a single route target is attached to the other BGP message, the PE router may shift this single route target from the other BGP message to the previously full BGP message so as to eliminate the need to disseminate multiple BGP messages to update the other PE routers' forwarding tables. Unfortunately, since the other PE routers have already imported multiple BGP messages in connection with this physical link, the other PE routers may misinterpret the decreased number of BGP messages as an indication that the physical link is no longer operational. As a result, the other PE routers may reconfigure their forwarding tables by removing the routes advertised in connection with the physical link instead of simply disassociating the EVPN represented by the removed route target from the physical link.
As another example, in the event that other route targets are still attached to the other BGP message, the PE router may shift a route target from the other BGP message to the previously full BGP message. The PE router may then disseminate the full BGP message and this other BGP message to update the other PE routers' forwarding tables. Unfortunately, since the other PE routers have already imported previous corresponding BGP messages in connection with this physical link, the other PE routers may reevaluate their import states and/or potentially misinterpret the changed set of route targets attached to the other BGP message as an indication that the physical link is no longer operational. As a result, the other PE routers may reconfigure their forwarding tables by removing the routes advertised in connection with the physical link instead of simply disassociating the EVPN represented by the removed route target from the physical link.
The instant disclosure, therefore, identifies and addresses a need for improved apparatuses, systems, and methods for preventing unintentional forwarding reconfiguration in network environments.